What prompted the chaos?

After both men left the stage, one journalist could be heard describing the scenes as "crazy".

After opening speeches by each fighter, Fury seemed to grow into proceedings and elected to stand to answer questions, during which he questioned why American Wilder's profile was small in his homeland despite his status as WBC world heavyweight champion.

"On Saturday night the whole world will know him as the person who Fury knocked out," said the Briton, 30.

"Up until he had 30 fights he was reserved. This swagger is not genuine, it's fake - a snide and a fraud. I look at him and don't see a bad man, I see a pretender."

Wilder - who had earlier said Fury had made his name in a "small country" - grew louder but remained seated.

But when the pair posed for head to heads, 33-year-old Wilder was shouting in his opponent's face, before a melee engulfed the stage.

Analysis - 'Wilder lost it'

BBC Radio 5 live analyst Steve Bunce

We've seen it before but I'm telling you now, you've never seen it with that much edge and nastiness.

Let's get this straight, Wilder lost it.

BBC Sport boxing correspondent Mike Costello

At times Wilder was thumping the desk when I spoke with him and this was half an hour after the news conference, he was still on fire.

View from the middle

Like Bunce, the feeling among the assembled media was that Wilder did indeed get provoked into losing his temper, and he took some time to re-establish his cool.

Showtime Boxing's Jim Gray, the man asking questions on stage, managed to evade the chaos when the fighters went head to head.

He told BBC Sport: "It reached a crescendo - it went to the edge, started to spill over but didn't go over the cliff.

"This is what happens. They go face to face, start screaming, it gets heated and takes on a life of its own.

"The longer you talk to one another in what is not common decency, adrenaline flowing, nothing good is going to happen."

What happened before the melee?

The state of frenzy in the huge conference room was mingled with shock at the way things escalated.

What is being hyped as the biggest heavyweight bout on US soil since Lennox Lewis overcame Vitali Klitschko in 2003 had seen both men remain largely respectful until this.

In such a vast city, it would be wrong to say the fight has gripped the public to date, although with Friday's weigh-in intensified by the fact it is open to the public, the customary head to head will now be under the microscope.

Wednesday's news conference came three years to the day since Fury beat Wladimir Klitschko, a win he has said owed partly to the mind games he deployed at news conferences in the build up.

The Briton referenced the mental health issues he has overcome since then and said it is now his "mission" to represent vulnerable people, insisting he would knock out Wilder.

"I stand as more than a champion - an ambassador for mental health. I am the people's champion," said Fury.

"I am not just fighting for me, I have millions of people that look up to me.

"I've heard a lot of people say Wilder by KO or Fury by points. I am telling you now, Wilder is getting knocked out."

Wilder - who was still screaming when organisers tried to end the questioning prior to the face off - said Fury "had his time" in 2015 when he ended Klitschko's 11-year unbeaten reign.

"He has has never faced someone with my mindset, with my power," the 33-year-old told BBC Sport. "I've been doing this a long time. I know what fear looks like, I can identify it. He is scared and he should be.

"This is a moment I have waited for for my entire career. This is the time, my time. Fury has had his window.

"Now I am here. I'll be damned if I come and let a man from another country come and upset what I have built.

"He says he will knock me out but I don't believe he will have the confidence. He speaks it but doesn't believe it. When I say it you can believe it, my numbers don't lie. I will knock Tyson Fury out."

Both men are expected in the ring at around 04:30 GMT on Sunday morning in the UK. Wilder will put his title on the line and look to defend a perfect 40-fight record, while Fury is also undefeated in 27 contests.